Automatic circuit breaker



July 30, 1940. J. SACHS in" AL AUTOMATIC CIRCUIT BREAKER oiiginal Filed April 15, 1938 2 Sheets-Sheet l Invent ars pf? Paw] 1 Christ 5275527 July 30, 1940. J. SACHS ET AL AUTOMATIC CIRCUIT BREAKER m 2 A M m m 5 4 W m A w h S 2 Original Filed April 15, 1938 n w w 5 n w? r 0 Q 5/: C

n w w a Z mby ami $1 dpfi Patented July 30, 1940 UNITED STATES PATENT OFFICE AUTOMATIC cnworr BREAKER necticut Application April 15, 1938, Serial No. 202,295 Renewed October 26, 1939 20 Claims. The present invention relates particularly to a I circuit breaker having the general characteristics of that disclosed in the co-pending application of Joseph Sachs for Automatic circuit breakers, Serial No. 152,020, filed July 6, 1937.

One general object of the present invention is to provide a circuit breaking mechanism which is adapted to open the circuit more quickly upon the occurrence of severe overload. In circuit breakers of the type disclosed in the above mentioned Sachs application, at least one of the contacts is provided with a mounting which yields as the contacts engage and which has sumcient resiliency to provide the required contact pressure. Upon the occurrence of an overload, the circuit breaking mechanism is released and operates to move one of the contacts away from the other; but on account of the resilient mounting of one or both of the contacts, actual separation of the contacts is momentarily delayed. In a circuit breaker embodying the present invention, as will appear from the following description, the contacts are rigidly mounted and a yieldable resilient element is associated with the operating mechanism, theresult being that there is a complete avoidance of that delay in contact separation which has heretofore occurred by reason of the resilient mounting of the contacts.

Another general object of the present invention is to provide certain improved structural details which reduce the cost of manufacture and which provide more effective operation. A more specific object of the invention is to provide an improved mechanical structure for the movable contact member. Another specific object of the present invention is to provide an improved inher. frame for supporting the circuit breaker mechanism. 0ther specific objects of the invention will be apparent from the following specification and claims.

In the accompanying drawings we have shown the embodiments of the invention which we now deem preferable, but it will be understood that the drawings are intended for illustrative purposes only and are not to be construed as defining or limiting the scope of'the invention, the claims forming a part of this specification being relied upon for that purpose. 1

Of the drawings:

Fig. 1 is a front view of an automatic circuit breaker embodying the invention, with certain parts broken away to show other parts more clearly.

Fig. 2 is a vertical sectional view taken along the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary vertical sectional view similar to Fig. 2, but showing the parts in the positions which they assume upon automatic opening while the handle is held in closed-circuit position.

Fig. 4 isa view similar to Fig. 3, but showing all of the parts including the handle in opencircuit positions.

Fig. 5 is a perspective view of theinner frame which carries the circuit breaking mechanism.

Fig. 6 is a fragmentary side view of a portion of the conducting contact carrying element and of the partition through which it extends.

Figs. 7 and 8 are views showing successive relative positions of the contact carrying element and of the partition during assembly.

Fig. 9 is a view showing various elements of the circuit breaking mechanism and associated parts separated from each other.

Fig. 10 is a fragmentary sectional view taken along the line l0l0 of Fig.2.

In describing the automatic circuit breaker as shown in the drawings we will first describe the principal parts of the circuit breaking mechanism, referring only briefly to the associated parts, such as the housing, the inner supporting frame and the muflier' device. Thereafter these associated parts will be described in greater detail.

A stationary main contact I is provided and. also a stationary conductor 2 which is separated from the contact. The contact I' and the conductor 2 are bothmounted upon a suitable base or housing. Directly connected electrically with the stationary conductor 2 is a flexible conductor 3. For making and breaking the circuit between the contact I and the conductors 2 and 3 there is provided a contact member which is pivotally movable about a fixed axis. The said contact member comprises a conducting element 4 which carries a movable contact 5 adapted to engage and disengage the stationary contact I.

The conducting element 4 is preferably formed of sheet metal and may advantageously be bent so as to have a U-shape in transverse section as shown in Fig. 9. The legs 4, 4 of the U extend forward and these legs are connected at the rear by a yoke which has an aperture 6 therein, thus providing two separated transverse yoke portions 4 and 4. The before mentioned movable contact 5 is carried by the transverse yoke portion U at the center thereof.

For supporting the contact member and associated parts there is provided an inner frame hereinafter described in greater detail. This frame includes two opposite similar insulating plates 1, l spaced apart and connected with each nther hv r sverse members 8, 9, l0 and l I. The 55 transverse member 8 is a pivot or bearing member which extends through holes 8, 8 in the legs of the conducting element 4, thus providing a pivotal support for the entire contact member. Surrounding the member 8 is a coil spring l2 which engages the conducting element 4 and also engages the insulating transverse member 9, this spring thus serving to bias the contact member in the, contact disengaging or circuit opening direction.

A handle or operating member I3 is pivotally supported on the said inner frame, the transverse member Ifl being utilized as the pivotal. 'support. The operating member I3 is biased in the clockwise direction by a spring I4.

In order that the operating member I3 may operate the contact member, there is provided a connecting mechanism which includes an actuator I5 which iscontrolled by means of a bimetallic element I6 bodily movable with the contact member. Preferably and as shown the bimetallic element I6 serves in and of itself as a latch, cooperating directly with the actuator I5 which isfimechanically connected with the contact member, being pivotally mounted at H between the two legs 4, 4 of the conducting element 4. The actuator is insulated from the legs 4*, 4 by means of insulating bushings I I I I which surround the pivot pin IT as shown in Fig. 10. These'bushings have shoulders thereon which serve to hold the actuator in central position. The actuator I5 has a portion which extends rearward and projects through the aperture 6 in the conducting element 4.

A link I8 is pivotally connected with the operating member I3 at I9 and with the actuator I5 at 20. With the parts in the normal closedcircuit position asshown in Fig. 2, the pivotal axis at I9 is above or in front of a straight line connecting the pivotal axes at I0 and 20, the operating member itself thus cooperating with the link I8 to form a normally locked or overset toggle. The before-mentioned transverse member II engages a suitable shoulder on the operating member to limit movement thereof in the counter-clockwise direction. The before-mentioned bi-metallic latch I6 normally engages the actuator I5 and holds it in its normal relationship with the other parts as shown in Fig. 2. In accordance with the present invention the latch is rigidly secured by brazing or otherwise to an integral downward extension 4 on the yoke portion 4 of the conducting element 4. The latch is thus connected near the pivot end of the conducting element, and it extends substantially parallelly therewith to its point of engagement with the actuator I5. The before-mentioned flexible conductor 3 is electrically connected directly with the bi-metallic latch I6 near the upper latching end. thereof. This connection may be eifected by brazing.

With the circuit breaker-in closed-circuitposition as shown in Fig. 2 it will be apparent that electrical connection is established from the stationary contact I to the movable contact 5, thence through the conducting element 4 and the bl-metallic latch I6, and thence through the flexible conductor 3 to the stationary conductor 2. As already stated, the contact member is biased in the circuit-opening direction by means of the spring I2, and the operating member is biased in the clockwise or circuit-opening direction by means of the spring I4. However, actual movement in the circuit-opening direction is normally prexented by reason of the described overset toggle relationship between the operating member itself and the link I8, it being understood that the latch I6 normally holds the actuator I5 fromrelative movement in the clockwise direction. Normally the operating member I3 may be moved to move the contact member and thus open or close the circuit. During such normal movements the latch I6 remains engaged with the actuator I5.

If the handle or operating member be held in its closed-circuit position as shown in Figs. 2 and 3 and if an abnormal current condition such as an overload is attained, the bi-metallic latch I6 is automatically deflected rearward as indicated in Fig.'3 so as to disengage and release the actuator I5. This deflection ordinarily occurs chiefly by reason of the heating of the bi-metallic element. Deflection may also occur by magnetic repulsive action between the bi-metallic element and the conducting element 4, as explained in detail in the said Sachs application, Serial No. 152,020. When the actuator is no longer held by the latch I6, the entire contact member is moved by the spring I2 in its open-circuit position as shown in Fig. 3, the actuator I5 and the linkv I8' assuming the relative positions shown in that figure. If the operating member be released after the parts have moved to the relative positions shown in Fig. 3, the spring I4 moves the operating member to the position shown in Fig 4, this in turn moving the link I8 and the actuator I5 to the positions shown in that figure. The actuator is thus restored to engaged or engageable relationship with the bimetallic latch I5.

The operation has been described as it occurs when the handle is first held and then released. Ordinarily, however, the operating member is not held and it starts to move to its open-circuit position as soon as the actuator has moved far enough in the clockwise direction to break the locking relationship between the operating member I 3,and the link I8. All of the parts thus 1 move practically instantaneously to the position shown in Fig. 4, the actuator being immediately restored to engaging relationship with the latch. As soon as the latch has cooled sufllciently the operating member can be' moved to again close the circuit.

In order to adjust the bi-metaliic latch I6 for purposes of calibration it may be desirable to provide an adjusting screw 2| extending through a threaded hole in the latch and in the yoke extension 4 This screw abuts against a plate 22 extending transversely between the legs 4 4 of the conducting element. It will be apparent that by adjusting the screw 2I the extension 4 may be deflected and the latch I6 may be moved within certain narrow limits so as to change its relationship upon the actuator and so as to be adapted to release the actuator upon the attainment of a definite predetermined overload condition.

In a circuit breaker of the general character herein shown and described, it is necessary to provide resiliently acting means for insuring the required pressure between the contacts. As disclosed in the before-mentioned Sachs application, Serial No. 152,020, the contacts themselves are resiliently mounted. The substantially stationary contact corresponding to the contact I of the present construction is yieldably mounted by means of a resilient supporting element and the movable contact corresponding to the contact 5 of the present construction is connected with the main portion of the contact member by means of a yieldable resilient element. It is therefore apparent that on account ofthe resilient mounting of the contacts they fail to separate instantly upon movement of the main element of the contact member; that is, after the main element of the contact member starts to move in the circuit-opening direction the contacts themselves remain engaged until their resilient supports have attained their free or unflexed condition. This delay in the separation of the contacts is exceedingly short, but it is very important in the event of an excessively heavy overload such as a short circuit. Under short circuit conditions a substantially instantaneous separation of the contacts is necessary in order to avoid injury to the bi-metallic strip and in order to avoid extensive burning of the contacts themselves.

In accordance with the present invention the stationary contact I is rigidly or fixedly secured in place so that no appreciable movement is possible, and the movable contact is rigidly secured to the main element 4 of the contact member so that it cannot move relatively thereto. In lieu of resiliently mounting the contacts themselves, we provide the necessary resiliency in or in'association with the train of mechanism for moving and holding the contact member, this train of mechanism including the operating member such as I3, the link such as i8, and the electro-responsively controlled mechanical connection such as the bi-metallic element or latch I6 and preferably also including the actuator such as Hi.

We do not narrowly restrict ourselves as con-- shown in Fig. 4 to the closed-circuit position shown in Fig. 2, the contacts are brought into engagement just before the toggle reaches its dead center position. Continued pressure on the handle or operating member serves to compress the link |8 until the dead center position is reached, the link serving to apply the required contact pressure. When the handle or operating member is moved beyond the dead center position to the position shown in Fig. 2 the force resiliently applied by the link I8 serves not only to maintain the contact pressure but also to hold the toggle in the overset position as shown.

Upon the occurrence of an overload, the bimetallic element or latch i6 is deflected in such manner as to permit the toggle to move out of its overset relationship and to thus permit the contact member with its contact to automatically move to open-circuit position. When the bimetallic element or latch is constructed and arranged as herein shown and described, it is deflected rearward so as to disengage the actuator IS in the manner already described. It will be apparent that the contact member, including the movable-contact 5, will start to move in the forward direction and will cause separation of the contacts instantly upon the release oi the actuator. There is no delay whatsoever on account of any resilient mounting of the contacts. The release of the actuator permits the link l8 to resume its uncompressed or unfiexed condition, but this obviously causes no delay in the movement of the contact member.

The circuit breaking mechanism which has thus far been described may be mounted in various ways and may be used for various purposes. In the drawings there is disclosed one suitable construction for supporting and enclosing the mechanism and there is also disclosed a suitable arc muiiiing device for use therewith. The supporting and enclosing construction and also the arc mutlling. device will now be described in detail, but it will be understood that as to 'these features we do not necessarily limit ourselves to the exact mechanism which has been described.

A main base or housing 23 is provided which supports the circuit breaking mechanism and all of the conducting parts. As shown this is an integral structure comprising a rear wall 23 and two forward projecting side walls 23', 23 which are spaced apart and which are identical in construction. The housing has a front cover 24 which may be of metal, an insulating sheet 25 being interposed between the cover and the housing. The cover 24 and the sheet 25 will be referred to collectively as constituting the front cover plate. The front cover plate is held in place by screws 26, 26 and it has an opening through which the operating member I 3 projects.

The housing 23 is secured to a rear metallic supporting plate 21 by means of the said screws 26, 26 the said plate 21 being in turn secured by means of screws 28, 28 to the rear wall of an outer metallic casing 29. The casing 29 has an openable front cover 30 secured by screws 3!, 3|, the said cover preferably having a central depressed portion 30 closely adjacent the housing front cover plate. The cover 30 also has an opening for the operating member l3.

The before-mentioned stationary contact I is carried by a relatively heavy stationary conductor 32 located near the upper end of the base or housing 23 and held in place by a screw 33. The conductor 32 may rest directlyagainst a portion of the housing as shown. Thus the contact is rigidly supported so that it cannot yield when pressure is applied. A wire terminal 34 cooperates with the conductor 32, being held in place by the screw 33. The before-mentioned stationary conductor 2 is secured to the base or housing 23 near the lower end thereof by means of a screw 35. A wire terminal 36 cooperates with the conductor 2, being held in place by the screw 35.

A mechanism supporting inner frame is provided, this being positioned between the main side walls 23", 23 of the housing. The inner frame includes the before-mentioned side plates 1, I and it also includes end plates 31 and 38 which are directly connected with the side plates independently of the housing 23 so as to provide a rectangular chamber. As shown, the end plates have slots into which project tongues I and I on the side plates, the tongues being of such size as to snugly fit the slots. Fig. 5 shows the inner frame separately from any other parts. The circuit breaking mechanism is positioned chiefly in the chamber bounded at the rear by the housing rear wall, bounded at the sides by the frame side plates 1, I and by the housing side walls, and bounded at the top and bottom by the frame end plates 31 and 38. The rear wall 23 of the housing has an opening at 23 which provides access to the adjusting screw 2| when the parts are in open-circuit positions as shown in Fig. 4. The hole 23 may be closed by a removable disc of insulating material.

The edge portions of. the end plates 31 and 38 of the inner frame enter opposed slots in the inner faces of the housing side walls as shown in Fig. 1. The rear edge of the plate 31 is seated in a transverse groove in the housing as shown I in Fig. 2, and the rear edge of the plate 38 engages the rear ends of the corresponding opposed slots in the housing walls. Thus the housing itself engages the inner frame and particularly the end plates thereof so as to' prevent rearward movement of the frame. Forward movement of the frame is normally prevented by the front cover plate which engages the front edges of the frame plates. Upon removal of the front cover plate the inner frame and all parts carried thereby can be freely moved in the forward direction. ible conductor 3, but complete removal of the inner frame and of the mechanism is possible when the conductor 2 is disconnected from the housing.

By reason of the aperture 6 therein, the conducting element 4 is in effect bifurcated at its upper end, the bifurcations being connected by the yoke portion 4' The bifurcations project upward through slots 31, 31 in the transverse end plate 31 and as before stated the operating member, l3 projects forward through the opening in the front cover plate. The stationary contact and the movable contact 5 are positioned outside of the above defined chamber. Thus the end plate 31 serves as a partition to separate the arcing zone at the contacts from the mechanism of the circuit breaker.

Fig. 6 shows the normal relationship between the contact carrying conducting element 4 and the partition plate 31. In this position the bifurcations of the conducting element extend through the slots 31, 31. In order that the parts may be assembled, the plate 31 is slitted at 31 31 and. at 31, 31. In assembling the conducting element 4 with the plate 31, the two portions of the plate are bent or deflected at the slits as, indicated'in Fig. 7 and the conducting element is turned sidewise as shown. After being inserted between the slitted portions of the plate 31 as shown in Fig. 7, the conducting element is then turned to the position shown by full lines in Fig. 8 and is then pushed rearward to the position shown by. dotted lines in the same figure. Thereupon the bifurcations of the conducting element snap into the slots 31, 31 and the portions of the plate 31 spring back into the same plane. We preferably provide the transverse slits 31, 31 as well as the longitudinal slits 31 31 so that the front end portion of the plate may extend without interruption entirely across the frame and into the corresponding grooves in the housing.

Preferably an arc muflling device is positioned immediately above the plate 31 as shown in Figs. 1 and 2, this device being. in the main at the front of the two contacts. Preferably the arc mufliing device is a separate structure normally held in place by the front cover plate, but being removable as a unit after the cover plate has been removed. The mufliing device is positioned between the side walls of the housing and below shoulders 23,23 formed on the said side walls.

Such movement is limited by the flex- The are muflling device comprises an insulating sheet 39 bent to provide a rear wall 39 and two opposite parallel side walls 39, 39. There is also provided an upper insulating sheet 40, which is preferably separate from the sheet 39. The rear wall 39 has an opening 39 therein through which the contact projects when the arc muflling device is in place. Carried by the opposite walls 39, 39 are metallic plates 4|, 4| oppositely positioned so as to provide a circuitous or serpentine passageway as clearly shown in Fig. 2. Preferably the side walls 39 39 have slots -or aperturestherein in which are seated the end portions of the plates 4|, 4|. The side walls of the housing preferably have opposite grooves 23, 23 for the ends of the plates 4|, 4| as shown in Fig. 1. 'The opposite side walls of the arc mufliing device have notches 39, 39 therein and the upper wall 40 has a notch 40 therein. The side main walls of the housing have notches 23, 23 registering with the notches 39, 39.

When the movable contact 5 is moved away from the stationary contact I, either manually or automatically, any arc-formed gases are forced to move in a generally forward direction through the serpentine passageway between the plates 4|, 4|. The gases can escape chiefly through the notches 39, 39 and 40. Thus the gases are guided in a serpentine or circuitous path so as to be cooled prior to being discharged from the circuit breaker housing.

What we claim is:

1. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a pivoted operating member and a link cooperating with each other to form a toggle which when in overset relationship holds the contact member in its closed-circuit position, means for biasing the toggle out of its overset relationship, a bimetallic strip carried by and movable with the contact member and having mechanical connection with the link so as to be adapted to normally maintain the toggle in its said overset relationship in opposition to its bias and to thereby maintain the contact member in closed-circuit position, the said bi-metallic strip being adapted to be automatically deflected upon the attainment of excess current conditions in the circuit so as to permit the linkto move and thus permit automatic movement of the contact member to its open-circuit position, the said operating member and the said link and the said bimetallic strip collectively constituting portions of a train of mechanism for moving and holding the contact member which train of mechanism has a yieldable resiliently acting element that serves as the toggle approaches its overset relationship to apply to the contact member the,

force necessary to provide the required pressure between the contacts.

2. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a movable actuator, an electro-responsively controlled mechanical connection movable with the contact member and engaging the actuator so as to enable the latter to efiect movement of the former to its closed-circuit or its open-circuit position, the said mechanical connection being adapted to beautomatically rendered inoperative upon the attainment of excess current conditions in the circuit so as to permit automatic movement of the contact member to its opencircuit position free from restraint by the actuator, an operating member pivotally movable about a substantially stationary axis, and a link pivotally connected with the actuator and with the operating member and cooperating with. the latter to form a toggle adapted when in overset relationship to normally hold the actuator and the contact member in their closed-circuit positions, the said operating member and the said link and the said actuator and the said electroresponsively controlled mechanical connection collectively constituting a train of mechanism for moving and holding the contact member which train of mechanism has a' yieldable resiliently acting element that serves as the toggle approaches its overset relationship to apply to the contact member the force necessary to provide the required pressure between the contacts.

3. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a movable actuator, a bi-metallic thermostatic strip carried by and movable with the contact member and engaging the actuator so as to enable the latter to eflect movement of the former to its closed-circuit or its open-circuit position, the' said bi-metallic strip being adapted to be automatically deflected upon the attainment of excess current conditions in the circuit so as to disengage the actuator and permit automatic movement of the contact member to its opencircuit position free from restraint by the actuator, an operating member pivotally movable about a substantially stationary axis, and a link pivotally connected with the actuator and with the operating member and cooperating with the latter to form a toggle adapted when in overset relationship to normally hold the actuator and the contact member in their closed-circuit positions, the said operating member and the said link and the said actuator and the said bi-metallic strip collectively constituting a train of mechanism for moving and holding the contact member which train of mechanism has a yieldable resiliently acting element that serves as the toggle approaches its overset relationship to apply to the contact member the force necessary to provide the required pressure between the contacts.

4. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, an actuator bodily movable with the contact member and also movable relatively thereto'about an axis transverse to the direction or bodily movement, a bi-metallic thermostatic strip carried by and movable with the contact member and engaging the actuator so as to enable the latter to effect movement of the former to its closed-circuit or its open-circuit position, the said bi-metallic strip being adapted to be automatically deflected upon the attainment of excess current conditions in the circuit so as to disengage the actuator and permit automatic movement of the contact member to its open-circuit position free from restraint by the actuator, an operating member pivotally movable about a substantially stationary axis, and a link pivotally connected with the actuator and with the operating member and cooperating with the latter to form a toggle adapted when in overset relationship to normally hold the actuator and the contact member in their closedcircuit positions, the said operating member and the said link and the said actuator and the said bi-metallio strip collectively constituting a train of mechanism for moving and holding the contact member which train of mechanism has a yieldable resiliently acting element that serves as the toggle approaches its overset relationship to apply to the contact member the force necessary to provide the required pressure between the contacts.

5. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a movable actuator, an electro-responsively controlled mechanical connection movable with the contact member and engaging the actuator so as to enable the latter to efiect movement of the former to its closed-circuit or its open-circuit position, the said mechanical connection being adapted to be automatically rendered inoperative upon the attainment of excess current conditions in the circuit so as to permit automatic movement of the contact member to its open-circuit position free from restraint by the actuator, an operating member pivotally movable about a stationary axis, and a link pivotally connected with the actuator and with the operating member and cooperating with the latter to form a toggle adapted when in overset relationship to normally hold the actuator and the contact member in their closed-circuit positions, the said toggle having a yieldable resiliently acting element that serves as the toggle approaches its overset relationship to apply to the contact memberthe force necessary to provide the required pressure between the contacts.

6. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a movable actuator, an electro-responsively controlled mechanical connection movable with the contact member and engaging the actuator so as to enable the latter to sheet movement of the former to itsclosed-circuit or its open-circuit position, the said mechanical connection being adapted to be automatically rendered inoperative upon the attainment of excess current conditions in the circuit so as to permit automatic movement of the contact member to its open-circuit position free from restraint by the actuator, an operating member pivotally movable about a stationary axis, and a link pivotally connected with the actuator and with the op r in memb r and cooperating with the latter to form a toggle adapted when in overset relationship to normally hold the actuator and the contact member in their closed-circuit positions, the said toggle link being resilient and of U-shape so as to be yieldable and so as to serve as the toggle approaches its overset relationship to apply to the contact member the force necessary to provide the required pressure between the contacts.

7. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a movable actuator, an electro-responsively controlled mechanical connection movable with the contact member and engaging the actuator so as to enable the latter to effect movement of the former -to its closed-circuit or its open-circuit position, the said mechanical connection being adapted to be automatically rendered inoperative upon the attainment of excess current conditions in the circuit so as to thereupon release the contact member from the actuator and permit it to automatically move to its open-circuit position free from restraint by the actuator, an operating member pivotally movable about a substantially stationary axis, a link pivotally connected with the actuator and with the operating member and cooperating with the latter to form' a toggle adapted when in overset relationship to normally hold the actuator and the contact member in their closed-circuit positions, the said operating member and the said link and the said actuator and the said electro-responsively controlled mechanical connection collectively constituting a train of mechanism for moving and holding the contact member which train of mechanism has a yieldable resiliently acting element that serves as the toggle approaches its overset relationship to apply the force necessary to hold the toggle in overset relationship and to provide the required 'pressure between the contacts, and means for breaking the overset relationship of the toggle and for moving the operating member and actuator to their open-circuit positions upon the diminution or absence of the aforesaid force resulting from the release of the contact member from the actuator.

8. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, an actuator bodily movable with the contact member and also movable relatively thereto about an axis transverse to the direction of bodily movement, a bi-metallic thermostatic strip carried by and movable with the contact member and engaging the actuator so as to enable the latter to efiect movement of the former to its closed-circuit or its open-circuit position, the said bi-metallic strip being adapted to be. automatically deflected upon the attainment of excess current conditions in the circuit so as to disengage the actuator and permit it to automatically move to its open-circuit position free from restraint by the actuator, an operating member pivotally movable about a stationary axis, a link pivotally tact member in their closed-circuit positions, the said toggle having a yieldable resiliently acting element that serves as the toggle approaches its overset relationship to apply the force necessary to hold the toggle in overset relationship and to provide the required pressure between the contacts, and means for breaking the overset relationship of the toggle and for moving the operating member and actuator to their open-circuit positions upon the release of the contact member from the actuator with the resulting diminution or absence of the aforesaid force.

9. The combination in an automatic circuit breaker, of a stationary contact, a contact member including a conducting element pivoted for movement about a fixed axis and also including a contact carried directly by the conducting eleconnected therewith near the pivotal axis thereof,

the said latch being normally engaged with the actuator but being automatically deflected from its normal relationship upon the attainment of abnormal current conditions in the circuit so as to disengage the actuator and thus permit automatic movement of the contact member to its open-circuit position free from restraint by the actuator, and means for operating the actuator to enable it in cooperation with the latch to normally effect the movement of the contact member to and from its closed-circuit position.

10. The combination in an automatic circuit breaker, of a stationary contact, a contact mem ber including a conducting element pivoted for movement about a fixed axis and also including a contact carried directly by the conducting element near one end and adapted to engage and disengage the stationary contact to close and open the circuit, means for biasing the said contact member toward its open-circuit position, an actuator connected with the conducting element for pivotal movement about. a transverse axis which is at the front of the element and-at a substantial distance from the said fixed axis and in fixed relation to the movable contact, the said actuator having a rearward extending portion, a bodily movable bi-metallic latch carried by the conducting element at the rear thereof and electrically connected in series with a portion of the said element, the said latch being normally engaged with the rearward extending portion of the actuator but being automatically deflected from its normal relationship upon the attainment of abnormal current conditions in the circuit so as to disengage the'actuator and thus permit auto member to and from its closed-circuit position.

11. The combination in an automatic circuit breaker, of a stationary contact, a contact member including a conducting element U-shaped in transverse section and pivoted for movement about a fixed axis and also including a contact carried directly by the conducting element near one end and adapted to engage and disengage the stationary contact to close and open the circuit, means for biasing the said contact member toward its open-circuit position, an actuator located between the legs of the U of the conducting element and pivoted for movement about a transverse axis which is at a substantial distance from the said fixed axis and in fixed relation to the movable contact, a bodily movable bi-metallic latch carried by the conducting element and electrically connected in series with a portion thereof, the said latch being normally engaged with the actuator but being automatically defiected from its normal relationship upon the attainment of abnormal current conditions in the circuit so as to disengage the actuator and thus permit automatic movement of the contact member to its open-circuit position free from restraint by the actuator, and means for operating the actuator to enable it in cooperation with the latch to normally effect the movement of the contact member to and from its closedcircuit position.

12. The combination in an automatic circuit breaker, of a stationary contact, a contact member including a conducting element pivoted for movement about a fixed axis and also including a contact carried directly by the conducting element near one end and adapted to engage and disengage the stationary contact to close and open the circuit, means for biasing the said contact member toward its open-circuit position, an actuator connected with the conducting element for pivotal movement about a transverse axis which is at the front of the element and at a substantial distance from the said fixed axis and in fixed relation to the movable contact, the said actuator having a rearward extending portion, a bodily -movable bi-metallic latch carried by the conducting element at the rear thereof and connected mechanically and electrically to an extension of the conducting element near the pivot portion thereof, the said latch being normally engaged with the rearward extending portion of the actuator but being automatically deflected rearward from its normal relationship upon the attainment of abnormal current conditions in the circuit so as to disengage the actuator and thus permit automatic movement of the contact member to its open-circuit position free from restraint by the actuator, and means for operating the actuator to enable it in cooperation with the latch to normally effect the movement of the contact member to and from its closed-circuit position.

13. The combination in an automatic circuit breaker, of a stationary contact, a contact member including a conducting element pivoted for movement about a fixed axis and also including a contact carried directly by the conducting element near one end and adapted to engage and disengage the stationary contact to close and open the circuit, means for biasing the said contact member toward its open-circuit position, an actuator connected directly with the conducting element for pivotal movement about a transverse axis which is at a substantial distance from the said fixed axis, and in fixed relation to the movable contact, the said actuator having a portion which extends rearward from its pivotal axis, a bodily movable bi-metallic laLch directly connected mechanically and electrically to the rear of the conducting element near the pivot ,portion thereof, the said latch being normally engaged with the rearward extending portion of the actuator but being automatically deflected rearward from its normal relationship upon the attainment of abnormal current conditions in the circuit s I deflecting a portion of the said conducting element to change the relationship of the bi-metallic latch with, respect to the actuator, and means for operating the actuator to enable it in cooperation with the latch to normally effect the movement of the contact member to and from its closed-circuit position.

14. In an automatic circuit breaker, the combination of a housing formed with a rear wall and with parallel side walls spaced apart, a plate substantially closing the housing at the front but having a handle opening therein, a supporting frame positioned behind the front plate and at least in part between the housing side walls and comprising two spaced side plates parallel with and closely adjacent the housing side walls and also comprising two spaced end plates, the said side plates being directly connected with the end plates independently of the housing to form a rectangular chamber, two conducting means positioned adjacent the respective end portions of the housing and supported independently of the frame, and an automatic circuit breaking mechanism carried by the frame at least in part within the said rectangular chamber and serving when in closed-circuit position to electrically connect the said two conducting means, the said mechanism having a movable handle at the front extending through the opening in the front plate.

15. In an automatic circuit breaker, the combination of a housing formed with a rear wall and with parallel side walls spaced apart, a plate substantially closing the housing at the front but having a handle opening therein, a supporting frame positioned behind the front plate and at least in part between the housing side walls and comprising two spaced insulating side plates parallel with and closely adjacent the housing side walls and also comprising two spaced insulating end plates, the said side plates being connected with the end plates independently of the housing to form a rectangular chamber and one of the said end plates being slotted, two conducting means positioned adjacent the respective end portions of the housing and supported independently of the frame, and an automatic circuit breaking mechanism carried by the frame at least in part within the said rectangular chamber and serving when in closed-circuit position to electrically connect the said two conducting means, the same mechanism having its contact carrying member extending through the said slot in one end wall of the frame and the said mechanism having a movable handle at the front extending through the opening in the front plate.

16. In an automatic circuit breaker, the combination of a housing formed with a 'rear wall and with parallel side walls spaced apart, a plate substantially closing the housing at the front but having a handle opening therein, a supporting frame positioned at least in part between the housing side walls and behind and in engagement with the front plate and being otherwise freely movable in the forward direction, the said frame comprising two spaced side plates parallel with and closely adjacent the housing side walls and also comprising two spaced end plates with which the side plates are directly connected independently of the housing to form a rectangular chamber, two conducting means positioned adjacent the respective end portions of the housing and supported independently of the frame, and an automatic circuit breaking mechanism carried by plate.

17. In an automatic circuit breaker, the combination of a housing formed with a rear wall and with parallel sidewalls spaced apart, a plate substantially closing the housing at the front but having a handle opening-therein, a supporting frame comprising two spaced side plates parallel with and closely adjacent the housing side walls and also comprising two spaced end plates with which the side plates are directly connected independently of the housing to form a rectangular chamber, the same frame being positioned at least in part between the housing side walls and behind and in engagement with the front plate and being otherwise freely movable in the forward direction and the said frame having the rear edges of its end plates in engagement with the housing to prevent rearward movement, two conducting means positioned adjacent the respective end portions of the housing and supported independently of the frame, and an automatic circuit breaking mechanism carried by the frame and freely movable in the forward direction when the frame is so moved, the said mechanism being at least in part within the said rectangular chamber of the frame and serving when in closed-circuit position to electrically connect the said two conducting means and the same mechanism having a movable handle at the front extending through the opening in the front plate.

18.. In an automatic circuit breaker, the combination of a housing formed with a rear wall and with parallel side walls spaced apart, the said side walls having two pairs of opposed grooves in their inner faces, a plate substantially closing the housing at the front but having a handle opening therein, a supporting frame positioned at least in part between the housing side walls and behind and in engagement with the front I plate and being otherwise freely movable in the forward, direction, the said frame comprising two spaced side plates parallel with and closely adjacent the housing side walls and also comprising two spaced end plates with which the side plates are directly connected independently of the housing to form a rectangular chamber, the edge portions of the said end platesbeing seated in the grooves in the housing side walls, two conductcuit position to electricaly connect the said two conducting means and the said mechanism having a movable handle .at the front extending through the opening in the front plate.

19. An automatic circuit breaker comprising in combination, a housing provided with parallel side walls spaced apart, an automatic circuit breaking mechanism positioned between the side walls of the housing and including a projecting bifurcated movable element with a yoke portion at the projecting end connecting the bifurcations, a movable contact carried by the said yoke portion, a stationary contact in position to be engaged and disengaged by the movable contact, and an insulating plate extending transversely with respect to the housing side walls and positioned to form a partition between the said contacts and the major portion of the circuit breaking mechanism, the said plate having longitudinal slots through which extend the bifurcations of the movable contact carrying element and the said plate being longitudinally slitted so as to permit portions thereof to be temporarily deflected sufficiently to permit entry of the bifurcations into the slots.

20. An automatic circuit breaker comprising in combination, a housing provided with parallel side walls spaced apart and having opposed grooves in their inner faces, an automatic circuit breaking mechanism positioned between the side walls of the housing and including a projecting bifurcated movable element with a yoke portion at the projecting end connecting the bifurcations, a movable contact carried by the said yoke portion, a stationary contact in position to be engaged and disengaged by the movable contact, and an insulating plate extending transversely with respect to the housing side walls and positioned in the said grooves to form a partition between the said contacts and the major portion of the circuit breaking mechanism, the said plate having longitudinal slots through which extend the bifurcations of the movable contact carrying element and the said plate having longitudinal slits in register with the slots and also having transverse slits extending from the longitudinal slits to the edges of the plate which slits permit portions of the plate to be temporarily deflected sufliciently to permit entry of the bifurcations into the slots.

JOSEPH SACHS. PAUL M. CHRIS'IENSEN. 

